Magnetic field driven enhancement of the weak decay width of charged pions

Abstract

We study the effect of a uniform magnetic field $$ \overrightarrow{B} $$ B → on the decays $$ {\pi}^{-}\to {l}^{-}{\overline{\nu}}_l $$ π − → l − ν ¯ l , where l− = e−, μ−, carrying out a general analysis that includes four π− decay constants. Taking the values of these constants from a chiral effective Nambu-Jona-Lasinio (NJL) model, it is seen that the total decay rate gets strongly increased with respect to the B = 0 case, with an enhancement factor ranging from ∼ 10 for eB = 0.1 GeV2 up to ∼ 103 for eB = 1 GeV2. The ratio between electronic and muonic decays gets also enhanced, reaching a value of about 1 : 2 for eB = 1 GeV2. In addition, we find that for large B the angular distribution of outgoing antineutrinos shows a significant suppression in the direction of the magnetic field.

Particle interaction strengths modified by magnetic fields

“…The above ideas are general in the sense that the asymptotic states, expressed in an useful form, help to extract in a simple way the magnetic field effects on more involved processes, as happens, for example, in the work presented in Ref. Coppola et al (2020) which deals with asymptotic charged states. There, the effect of an homogeneous external magnetic field on the charged pion decay width to leptons is analyzed $$$ \left({\pi}^{-}\to {l}^{-}{\overline{\nu}}_l\right) $$$.…”

Magnetic field effect on early universe events

“…The process is enhanced in some cases, as is extensively reported in the literature. I present here a non‐exhaustive list of results that go in in this direction: Tsai & Erber (1975), Urrutia (1978), Kuznetsov et al (1998), Mikheev & Chistyakov (2001), Erdas & Lissia (2003), Bhattacharya & Sahu (2009), Satunin (2013), Coppola et al (2020), Jaber‐Urquiza (2020), Züñiga (2020). These last two works are still in progress, having computed only the divergent term, after renormalization, among the huge list of terms generated by the magnetic field.…”